[knee-deep] or [neck-deep] {adv.} or {adj. phr.} 1. Very much; deeply; having a big part in. * /Johnny was knee-deep in trouble./ 2. Very busy; working hard at. * /We […]A Dictionary of American Idioms

[in deep] {adj. phr.} Seriously mixed up in something, especially trouble. * /George began borrowing small sums of money to bet on horses, and before he knew it he was […]A Dictionary of American Idioms